What Lives in Your Air Ducts?

Cleaning Air Ducts

If you think you and your family are your home’s only occupants, think again. The air ducts in your home are host to a variety of organisms, some benign in small amounts. However, in concentrated amounts, these organisms can negatively affect your indoor air quality, causing health problems and threatening the integrity of your home. Below, I’ll cover some of the organisms you’ll find in your air ducts, the causes, and how to clean and treat the problem.

Mold and Mildew

  • What are they? Mold and mildew are growths that thrive on moisture and reproduce by means of spores— which are essentially tiny seeds—that float through the air. Because of this method of reproduction, curbing the growth of mold can prove difficult. Unchecked growth can provoke allergic reactions in people.
  • What causes mold and mildew? As I mentioned above, mold and mildew like moisture, a lot of it. You’ll often see mold grow in your shower because of the moist conditions inherently present there.
  • How do I treat them? You cannot rid your home of mold entirely since spores will find a way in and will often float with other dust. However, you can control the growth of mold by controlling the amount of moisture in your home. Use the vent while showering, purchase a dehumidifier, and install a high MERV-rated filter in your furnace to weed out any spores. If mold has grown in your ducts, hire a professional to assess and address the situation.

Dust Mites

  •  What are they? Dust mites are microscopic creatures that feed on shed skin flakes. They tend to live in bedding, carpets, curtains, and upholstery.
  • Where do they come from? Dust mites like warm and humid environments, which is why they live where they live.
  • How do I treat them? You will never be able to make your home entirely dust mite-free, but you can decrease their numbers. Wash your bedding once a week in very hot water, dust with a damp cloth, use a dehumidifier to keep moisture levels low, install a high MERV-rated filter in your furnace, and zip your mattress and pillows into dust-proof covers.


  • What is it? Pollen is a fine to coarse powder made by plants in order to reproduce. If you’ve ever watched bees buzzing among flowers, you’ve likely noticed the furry parts of their bodies are covered in a powdery yellow substance. That’s pollen.
  • Where does it come from? Flowers produce pollen to propagate their species. Pollen can attach itself to bees, as I’ve mentioned, and it can also float through the air. On certain days, you may even notice your windshield is coated in a film of pollen. Airborne pollen comes mainly from anemophilous plants. Their pollen is lightweight and powdery, and dispersal is dependent on wind. Other plants have heavier, stickier pollen, and they rely on animals and insects to spread it. Airborne pollen is the type that triggers allergies.
  • How do I treat it? So, how to diminish airborne pollen? Well, like many of the things above, you can’t eradicate it completely. There are just some things we have to live with. However, to reduce the amount of pollen that enters your home, use a high MERV-rated furnace filter, close your doors and windows at night, and avoid hanging laundry out to dry in the backyard (pollen will get into the fabric). 


While it’s impossible to make your home completely free of allergens and other irritants, you can take steps to minimize their ubiquity. Using a high MERV-rated air conditioning filter will go a long way toward this goal, as will regular dusting and vacuuming.


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